DNA sequences for an amino acid transporter, plasmids, bacteria, yeasts and plants containing a transporter and their use

ABSTRACT

There are described DNA sequences that contain the coding region of amino acid transporters whose introduction in a plant genome modifies the transfer of metabolites in transgenic plants, plasmids, bacteria, yeasts and plants containing these DNA sequences, as well as their use.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to DNA sequences that contain the coding region of amino acid transporters, whose introduction in a plant genome modifies the transfer of metabolites in transgenic plants, plasmids, bacteria, yeasts and plants containing these DNA sequences, as well as their use.

For many plant species it is known that the delivery of energy-rich compounds to the phloem through the cell wall takes place throughout the cell. Transporter molecules which allow the penetration of amino acids through the plant cell wall are not known.

In bacteria, numerous amino acid transport systems have been characterized. For aromatic amino acids, 5 different transporters have been described which can transport any one of phenylalanine, tyrosine and tryptophan, while the other transporters are specific for individual amino acids (see Sarsero et al., 1991, J Bacteriol 173: 3231-3234). The speed constants of the transport process indicates that the specific transport is less efficient. For several transporter proteins, the corresponding genes have been cloned. This has been achieved using transport-deficient mutants which were selected for their transport ability after transformation with DNA fragments as inserts in expression vectors (see Wallace et al., 1990, J Bacteriol 172: 3214-3220). The mutants were selected depending on their ability to grow in the presence of toxic analogues of amino acids, since the mutants cannot take these up and therefore cannot be impaired.

Corresponding complementation studies have been carried out with the eukaryotic yeast, Saccharomyces cerevisiae. Tanaka & Fink (1985, Gene 38: 205-214) describe a histidine transporter that was identified by complementation of a mutation. Vandenbol et al. (1989, Gene 83: 153-159) describe a proline transporter for Saccharomyces cerevisiae. The yeast possesses two different permeases for proline. One transports with lower efficiency and can be used also for other amino acids, and the other is proline-specific and works with high affinity. The latter was coded from the put4 gene. This carries an open reading frame for a peptide with a molecular weight of 69 kDa. The protein contains 12 membrane-penetrating regions, but does not contain any N-terminal signal sequence for secretion. This is a typical property of integral membrane proteins. The permeases process homology for arginine and for histidine permease from yeast, but not, however, for proline permease from Escherichia coli.

For plant cells, based on studies on tobacco suspension cultures, it has been found that the transport of arginine, asparagine, phenylalanine and histidine are pH and energy dependent. Since a 1,000-fold excess of leucine inhibits the transport of the other amino acids, it can be assumed, therefore, that all amino acids use the same transporter (McDaniel et al., 1982, Plant Physio 69: 246-249). Li and Bush (1991, Plant Physiol 96: 1338-1344) determined, for aliphatic, neutral amino acids, two transport systems in plasma membrane vesicles from Beta vulgaris. On the one hand, alanine, methionine, glutamine and leucine displace each other on the transporter protein. On the other hand, isoleucine, valine and threonine have mutually competitive effects. In combined competition kinetic studies (Li & Bush, 1990, Plant Physiol 94: 268-277) four different transport systems have been distinguished. Besides a transporter for all neutral amino acids, which work with low affinity, there exists a high affinity type which, however, possesses low affinity for isoleucine, threonine, valine and proline. Further transporters exist for acids as well as for basic amino acids.

The transporter molecule or gene for plant transporter proteins is not known.

SUMMARY OF THE INVENTION

There are now described DNA sequences which contain the coding region of a plant amino acid transporter, and whose information contained in the nucleotide sequence allows, by integration in a plant genome, the formation of RNA, by which a new amino acid transport activity can be introduced in the plant cells or an endogenous amino acid transporter activity can be expressed.

Under the term amino transporter is to be understood, for example a cDNA sequence that codes an amino transporter from Arabidopsis thaliana.

The identification of the coding region of the amino acid transporter is carried out by a process which allows the isolation of plant DNA sequences which code transporter molecules by means of expression in specific mutants of yeast Saccharomyces cerevisiae. For this, suitable yeast mutants have to be provided which cannot take up a substance for which the coding region of the transporter molecule has to be isolated from a plant gene library.

A mutant which cannot grow in media, with proline or citrulline as the only nitrogen source, is described by Jauniaux et al. (1987), Eur J Biochem 164: 601-606).

For the preparation of yeast strains that can be used to identify plant amino acid transporters, a yeast mutant which is not able to grow in media with proline and/or citrulline as the only nitrogen source is, for example, transformed with pFL 61 plasmid, which carries, as an insert, cDNA fragments from a cDNA library from Arabidopsis thaliana.

Further, a double mutant JT16 (Tanaka & Fink, 1985, Gene 38: 205-214) which has a deficiency in histidine synthesis (his4) and in histidine uptake (hip1) is transformed with the described pFL 61 plasmid and cultivated in a medium with addition of histidine.

It has now surprisingly been found that, in the transformation of yeast cells, certain plant cDNA fragments can complement the yeast mutation. By analysis of the properties of the proteins coded from the cDNA it can be shown that a coding region that codes a plant amino acid transporter with a wide specificity spectrum is responsible for the complementing of the mutation (see example 3).

Such a coding region of an amino acid transporter is shown, for example, by one of the following nucleotide sequences: ##STR1##

The DNA sequences of the invention identified with the help of the transformed yeast strains, e.g., sequences Seq. No. 1and 2, can be introduced into plasmids and thereby be combined with steering elements for expression in eukaryotic cells (see Example 4). These steering elements are, on the one hand, transcription promoters, and, on the other hand, transcription terminators. Plasmids can be used to transform eukaryotic cells with the aim of expression of a translatable mRNA which makes possible the synthesis of an amino acid transporter in the cells or with the aim of expression of a non-translatable RNA, which prevents synthesis of an endogenous amino acid transporter in the cells. The expression of an RNA corresponding to the inventive sequences of plant amino acid transporters modifies the plant acid metabolism, as well as total nitrogen metabolism. The economic significance of this modification is obvious. Nitrogen is the nutrient mainly responsible for limiting growth. The viability of germ lines as well as germination capacity of seeds is directly dependent on the nitrogen content of storage tissue. The formation of high value food materials with a high protein content is dependent on a sufficient nitrogen supply. Nitrogen is transported essentially in the form of amino acids. An improvement in the delivery of amino acids to their harvested parts can therefore lead to an increase in yield of agricultural plants. The possibility of forcing the uptake of amino acid in individual organs allows the qualitative improvement of such organs, which, because of the demands of the utilization process, contain little nitrogen. An example is potatoes which are grown for the production of starch. Besides this, it is possible to modify the whole plant, by which the growth of individual tissues, for example, leaves, is slowed down, while the growth of the harvested parts is increased. For this, one can imagine a lengthening of the vegetative phase of crops, which leads to an increased formation of storage substances.

Processes for the genetic modification of dicotyledonous and monocotyledonous plants are already known (see for example Gasser, C. S., Fraley, R. T., 1989, Science 244: 1293-1299; Potrykus, 191, Ann Rev Plant Mol Biol Plant Physiol 42: 205-225). For expression in plants the coding sequences must be coupled with the transcriptional regulatory elements. Such elements, called promoters, are known (EP 375091).

Further, the coding regions must be provided with transcription termination signals with which they can be correctly transcribed. Such elements are also described (see Gielen et al., 1989, EMBO J 8: 23-29). The transcriptional start region can be either native and/or homologous or foreign and/or heterologous to the host plant. If desired, termination regions are interchangeable with one another. The DNA sequence of the transcription starting and termination regions can be prepared synthetically, obtained naturally, or can be a mixture of synthetic and natural DNA constituents. For introduction of foreign genes in higher plants, a large number of cloning vectors are available that include a replication signal for E. coli and a marker which allows for the selection of the transformed cells. Examples of such vectors are pBR 322, pUC-Series, M13 mp-Series, pACYC 184, etc. Depending on the method of introduction of the desired gene in the plants, other DNA sequences may be suitable. Should the Ti- or Ri-plasmid be used, e.g., for the transformation of the plant cell, then at least the right boundary, often, however, both the right and left boundary of the Ti- and Ri-Plasmid T-DNA, is attached, as a flanking region, to the gene being introduced. The use of T-DNA for the transformation of plant cells has been intensively researched and is well described in EP 120 516; Hoekama, In: The Binary Plant Vector System, Offset-drukkerij Kanters B. V. Alblasserdam (1985), Chapter V; Fraley, et al., Crit. Rev. Plant Sci., 4:1-46 and An et al. (1985) EMBO J. 4: 277-287. Once the introduced DNA is integrate in the genome, it is generally stable there and remains in the offspring of the original transformed cells. It normally contains a selection marker which induces resistance in the transformed plant cells against a biocide or antibiotic such as kanamycin, G 418, bleomycin, hygromycin or phosphinotricin, etc. The individual marker employed should therefore allow the selection of transformed cells from cells which lack the introduced DNA.

For the introduction of DNA into a plant host cell, besides transformation using Agrobacteria, there are many other techniques available. These techniques include the fusion of protoplasts, microinjection of DNA and electroporation, as well as ballistic methods and virus infection. From the transformed plant material, whole plants can be regenerated in a suitable medium which contains antibiotics or biocides for selection. The resulting plants can then be tested for the presence of introduced DNA. No special demands are placed on the plasmids in injection and electroporation. Simple plasmids, such as, e.g., pUC-derivatives, can be used. Should whole plants be regenerated from such transformed cells, the presence of a selectable marker gene is necessary. The transformed cells grow within the plants in the usual manner (see also McCormick et al. (1986) Plant Cell Reports 5: 81-84). These plants can be grown normally and crossed with plants that possess the same transformed genes or different genes. The resulting hybrid individuals have the corresponding phenotypical properties.

The DNA sequences of the invention can also be introduced in plasmids and thereby combined with steering elements for an expression in prokaryotic cells. The formation of a translatable RNA sequence of a eukaryotic amino acid transporter from bacteria, in spite of the considerable differences in the membrane structures of prokaryotes and eukaryotes, means that prokaryotes can now use a eukaryotic amino acid transporter with specificity for certain substrates. This makes possible the production of bacterial strains which could be used for studies of the properties of the transporter as well as its substrate.

The invention also relates to bacteria that contain the plasmids of the invention.

The DNA sequences of the invention can also be introduced in plasmids which allow mutagenesis or a sequence modification through recombination of DNA sequences in prokaryotic or eukaryotic systems. In this way, the specificity of the amino acid transporter can be modified. Thus, the specificity of the transporter can be changed.

The invention also relates to derivatives or parts of plasmids that contain the DNA sequences of the invention and which can be used for the transformation of prokaryotic and eukaryotic cells.

By using standard processes (see Sambrook et al., 1989, Molecular Cloning: A Laboratory Manual, 2d ed., Cold Spring Harbor Laboratory Press, N.Y., USA), base exchanges can be carried out or natural or synthetic sequences can be added. For binding DNA fragments with one another, adaptors or linkers can be introduced on the fragments. Further, manipulations can be carried which prepare suitable restriction cleavage sites or remove the excess DNA or restriction cleavage sites. Where insertions, deletions or substitutions such as, for example, transitions and transversions are desired, in vitro mutagenesis, primer repair, restrictions or ligations can be used. For methods of analysis, in general, a sequence analysis, restriction analysis and other biochemical molecular biological methods can be used. After each manipulation, the DNA sequence used can be cleaved and bound with another DNA sequence. Each plasmid sequence can be cloned in the same or different plasmids.

Derivatives or parts of the DNA sequences and plasmids of the invention can also be used for the transformation of prokaryotic and eukaryotic cells. Further, the DNA sequences of the invention can be used according to standard processes for the isolation of similar sequences on the genome of plants of various species, which also code for amino acid or other oligosaccharide transporter molecules. With these sequence constructs, for the transformation of plant cells, can be prepared which modify the transport process in transgenic plants.

In order to specify related DNA sequences, gene libraries must first be prepared which are representative of the content of genes of a plant type or for the expression of genes in a plant type. The former are genomic libraries, while the latter are cDNA libraries. From these, related sequences can be isolated using the DNA sequences of the invention as probes. Once the related gene has been identified and isolated, a determination of the sequence and an analysis of the properties of the proteins coded from this sequence is possible.

In order to understand the examples forming the basis of this invention all the processes necessary for these tests and which are known per se will first of all be listed:

1. Cloning Process

For cloning in E. coli, the vector pBluescriptSK (Short et al., 1988, Nucl Acids Res 16: 7583-7600) was used.

For the transformation of yeasts, the vector pFL61 (Minet & Lacroute, 1990, Curr Genet 18: 287-291) was used.

For the plant transformation the gene constructs in the binary vector pBIN-Hyg were cloned.

2. Bacterial and Yeast Strains

For the pBluescriptSK vector as well as for PBinAR constructs, the E. coli strain XL1blue (Bullock et al., 1987, Biotechniques, 5, 376-378) was used.

As a starting strain for the expression of the cDNA library in yeast, the yeast strain 22574d (Jauniaux et al., 1987 Eur J Biochem 164: 601-606) was used.

The transformation of the plasmids in potato plants was carried out using Agrobacterium tumefaciens strain LBA4404 (Bevan (1984) Nucl. Acids Res 12: 8711-8720).

3. Transformation of Agrobacterium tumefaciens

The transfer of the DNA in Agrobacteria was carried out by direct transformation by the method of Hofgen & Willmitzer (1988, Nucleic Acids Res 16: 9877). The plasmid DNA of the transformed Agrobacterium was isolated in accordance with the method of Birnboim and Doly (1979) (Nucl Acids Res 7: 1513-1523) and was analyzed by gel electrophoresis after suitable restriction cleavage.

4. Plant Transformation

Ten small leaves, wounded with a scalpel, of a sterile potato culture were placed in 10 ml of MS medium with 2% amino acid containing 30-50 μl of an Agrobacterium tumefaciens overnight culture grown under selection. After 3-5 minutes of gentle shaking, the leaves were laid out on MS medium of 1.6% glucose, 2 mg/1 of zeatin ribose, 0.02 mg/l of naphthylacetic acid, 0.02 mg/l of gibberellic acid, 500 mg/l of claforan, 50 mg/l of kanamycin and 0.8% bacto agar. After incubation for one week at 25° C. and 3000 lux, the claforan concentration in the medium was reduced by half.

Deposits

The following plasmids and yeast strains were deposited at the Deutschen Sammlung yon Mikroorganismen (DSM) in Braunschweig, Germany on 12.06.1992 (deposit number):

    ______________________________________                                         Plasmid      pPPP1-20       (DSM 7129)                                         Plasmid      pBinPPP1-20    (DSM 7130)                                         ______________________________________                                    

Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the plasmid pPPP1-20 which contains the sequence Seq-ID No. 1. The finely drawn line corresponds to the sequence from pBluescriptSK. The thicker line represents the cDNA insert. The cleavage positions of the inserts are shown.

FIG. 2 shows the uptake of ¹⁴ C-proline from the medium.

no=time period of the uptake without competitor;

proline=time period with fourfold excess of unlabeled proline;

citrulline=time period with fourfold excess of unlabeled citrulline;

GABA=time period with fourfold excess of gamma-aminobutyric acid;

time=time in seconds;

cpm=decays counted per minute.

FIG. 3 shows the plasmid pAAP2 which contains the sequence Seq-ID No. 2. The finely drawn line corresponds to the sequence from pBluescriptSK. The thicker line represents the cDNA insert. The cleavage positions of the inserts are shown.

FIG. 4 shows a competition experiment with the yeast line 22574d::AAP2. In this experiment, the uptake of ¹⁴ C-labeled L-proline from the medium in the presence of a fourfold excess of other amino acids or their analogues is measured. Besides the standard abbreviations for amino acids in the three letter code, the following are also used:

Cit=citrulline;

D-Pro=D-proline;

OH-Pro=hydroxyproline; and

AC2=azetidine-2-carboxylic acid.

FIG. 5 shows a competition experiment with the yeast line JT16::AAP2. In this experiment, the uptake of ¹⁴ C labeled L-histidine from the medium in the presence of a tenfold excess of other amino acids or their analogues is measured.

Besides the standard abbreviations for amino acids in the three letter code, the following are also used:

Cit=citrulline;

Orn=ornithine;

Can=canavanine; and

NH4=ammonium.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples describe the cloning and identification, as well as the function and use of a plant amino acid transporter.

EXAMPLE 1 Cloning of the cDNA of a Plant Amino Acid Transporter

For complementation of the proline transport mutation of the yeast strain 22574d (Jauniaux et al., 1987, Eur J Biochem 164: 601-606) and/or the histidine synthesis and transport mutation of the strain JT16 (Tanaka & Fink 1985, Gene 38: 205-214), a cDNA of young germ lines from Arabidopsis thaliana (two leaf stage) in the yeast expression vector pFL61 (Minet & Lacroute), 1990 Curr Genet 18: 287-291) which had been made available by Minet (Minet et al., 1992, Plant J 2: 417-422) was used. Around 1 μg of the vector with the cDNA-insert was transformed in the yeast strain 22574d and/or JT16 by the method of Dohmen et al. (1991, Yeast 7: 691-692). Yeast transformands, which could grow in media with 4 mM proline as the sole nitrogen source or in media with 6 mM histidine, were propagated. From the lines plasmid-DNA was prepared by standard methods. Clones that could complement the particular mutation contained plasmids with similar restriction type of the cDNA insert. These varied in size between 1.6 and 1.7 kb.

EXAMPLE 2 Sequence Analysis of the cDNA Insert of the Plasmid DFL61-ppp1-20

From a yeast line PPP1-20, obtained in a similar manner to example 1, which, in spite of the 22574d mutation, could grow with proline as the only nitrogen source, the plasmid pFL61-ppp1-20 was isolated. Its cDNA insert was prepared as a NotI fragment and cloned in the vector pBluescriptSK. In this way, the plasmid pPPP1-20 was obtained (see FIG. 1). Using synthetic oligonucleotides, the insert was sequenced by the method of Sanger et al. (1977, Proc Natl Acad Sci USA 74:5463-5467). The sequence is given above (SEQ ID No. 1).

In a similar way, from a yeast line that, in spite of the his4/hip1 double mutation, could be grown in a medium with histidine addition, the plasmid pFL61-aap2 was isolated whose insert was also cloned as a NotI fragment in pBluescriptSK. The resulting plasmid pAAP2 was sequenced and the sequence (SEQ ID No. 2) is given above. The plasmid pAAP2 has a similar structure to pPPP1-20 (see FIG. 1), but instead of the insert SEQ ID No. 1, carries the insert SEQ ID No. 2 (see FIG. 3).

EXAMPLE 3 Uptake Studies with ¹⁴ C-Labeled Protein into the Yeast Line PPP1-20 and AAP2

The yeast lines 22574d::PPP1-20 and 22574d::AAP2 that were obtained in a similar manner to Example 1 were grown in liquid medium until the culture reached the logarithmic phase. After centrifuging the culture, the cells are washed and taken up in 100 mm tris/HCl pH 4.5, 2 mM MgCl₂ and 0.6M sorbitol. Around 100 μL of the suspension was added to a solution of 0.5mM L-proline plus 1 μCi ¹⁴ C labeled L-proline in 100 μL of the same buffer. The uptake of the labeled amino acid was measured by the process described by Cirillo (1989, Meth Enzymol 174: 617-622). The uptake of the labeled amino acid was compared, on the one hand, in co-incubation with protein modifying substance diethyl pyrocarbonate which is an inhibitor of the amino acid transport in membrane vesicles from Beta vulgaris, and, on the other hand, in co-incubation with other protein modifying substances. The calculated reduction is shown in Tables I and/or III. A competition experiment in which the specificity of the transporter could be read off with various amino acids and analogues is shown in Table II for PPP1-20 and in FIG. 4 for AAP2. An analogous experiment in which a competition for histidine uptake in the line JT16::AAP2 was tested is described in Example 5. The time period for PPP1-20 is shown in FIG. 2.

EXAMPLE 4 Transformation of Plants with a Construct for Overexpression of the Coding Region of Amino Acid Transporters

From the plasmid pPPP1-20 that contains the cDNA for the amino acid transporter from Arabidopsis, an internal fragment of the insert was isolated after BamHI cleavage and cloned in the BamHI cleavage position from pAJ that was first linearized with the enzyme BamHI. Then the cDNA was prepared as the EcoRI/HindIII fragment from pA7 and cloned in the vector pBIN-HYG. After transformation by. Agrobacteria, this was inserted for infection of leaf segments of tobacco and potato.

Ten independently obtained transformands in which the presence of the intact non-rearranged chimeric gene was demonstrated using Southern blot analysis were tested for modifications of amino acid and nitrogen content. Besides this, amino acid synthesis, photosynthesis rate and transportation were tested.

EXAMPLE 5 Studies in the Uptake of ¹⁴ C-labeled Histidine in the Yeast Line AAP2

The yeast line JT16::AAP2, obtained in a similar manner to Example 1, was grown in liquid medium until the culture reached the logarithmic phase. After centrifuging the culture, the cells were washed and taken up in 10 mm tris/HCl pH 4.5, 2 mm MgCl₂ and 0.6M sorbitol. Around 100 ml of the suspension was added to a solution of 0.5 mm L-histidine plus 1 μCi ¹⁴ C-labeled L-histidine in 100 μL of the same buffer. The uptake of the labeled amino acid was measured according to the method described by von Cirillo (1989, Meth Enzymol 174: 617-622). The uptake of the labeled amino acid was compared in a competition experiment with that from different amino acids and analogues in tenfold excess. The relationships are shown in FIG. 5.

                  TABLE I                                                          ______________________________________                                         Inhibition of the amino acid transport in 22574d::PPP1-20                      yeast strains by protein modifying substances                                                           % of transport                                                                 without inhibitor                                     ______________________________________                                         0.1 mM DEPC              65                                                    (diethyl pyrocarbonate)                                                        10 μM CCCP            <3                                                    (Carbonyl cyanide m-chlorophenylhydrazone)                                     10 μM 2, 4 DNP        <3                                                    (Dinitrophenol)                                                                1 mM sodium arsenate     35                                                    10 μM antimycin A     29                                                    500 μM PCMBS          78                                                    (p-chloromercuribenzenesulfonic acid)                                          ______________________________________                                    

                  TABLE II                                                         ______________________________________                                         Competition by one, fourfold and tenfold excess of amino                       acids and analogues in 22574d::PPP1-20 - yeast strain                          Excess % remaining                                                             transport activity:                                                                             1×   4×                                                                             10×                                    ______________________________________                                         glutamic acid    64         27    30                                           aspartic acid    78               27                                           lysine           86               83                                           histidine        81         79    58                                           arginine         85         88    74                                           threonine        --         50    --                                           L-proline        49         21    14                                           D-proline        98               95                                           3, 4-di-OH proline                                                                              86               49                                           azetidine-                                                                     2-carboxylic acid                                                                               91               48                                           OH-proline       81               45                                           valine           --         77    47                                           isoleucine       --         67    --                                           asparagine       64               57                                           glutamine        --         27    --                                           serine           53               18                                           cysteine         --         21    --                                           methionine       28               8                                            glycine          69               16                                           alanine          55         29    23                                           leucine          --               --                                           tyrosine         --               --                                           tryptophan       82         71    48                                           phenylalanine    45               16                                           citrulline                  44                                                 gamma-aminobutyric acid     90                                                 ______________________________________                                    

                  TABLE III                                                        ______________________________________                                         Inhibition of the amino acid transports in JT16::AAP2 -                        yeast strain by protein modifying substances                                                     % of transport without inhibitor                             ______________________________________                                         1 mM DEPC         3.1 ± 1.6                                                 (Diethyl pyrocarbonate)                                                        10 μM CCCP     15.6 ± 2.1                                                (Carbonyl cyanide                                                              m-chlorophenylhydrazone)                                                       10 μM 2, 4 DNP                                                              (Dinitrophenol)   7.6 ± 1.6                                                 ______________________________________                                    

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. Therefore, the present invention is to be limited not by the specific disclosure herein, but only by the appended claims.

    __________________________________________________________________________     SEQUENCE LISTING                                                               (1) GENERAL INFORMATION:                                                       (iii) NUMBER OF SEQUENCES: 4                                                   (2) INFORMATION FOR SEQ ID NO:1:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 1685 base pairs                                                    (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arabidopsis thaliano                                             (ix) FEATURE:                                                                  (A) NAME/KEY: CDS                                                              (B) LOCATION: 57..1511                                                         (D) OTHER INFORMATION: /note= "amino acid transporter"                         (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                        CTTAAAACATTTATTTTATCTTCTTCTTGTTCTCTCTTTCTCTTTCTCTCATCACT56                     ATGAAGAGTTTCAACACAGAAGGACACAACCACTCCACGGCGGAATCC104                            MetLysSerPheAsnThrGluGlyHisAsnHisSerThrAlaGluSer                               151015                                                                         GGCGATGCCTACACCGTGTCGGACCCGACAAAGAACGTCGATGAAGAT152                            GlyAspAlaTyrThrValSerAspProThrLysAsnValAspGluAsp                               202530                                                                         GGTCGAGAGAAGCGTACCGGGACGTGGCTTACGGCGAGTGCGCATATT200                            GlyArgGluLysArgThrGlyThrTrpLeuThrAlaSerAlaHisIle                               354045                                                                         ATCACGGCGGTGATAGGCTCCGGAGTGTTGTCTTTAGCATGGGCTATA248                            IleThrAlaValIleGlySerGlyValLeuSerLeuAlaTrpAlaIle                               505560                                                                         GCTCAGCTTGGTTGGATCGCAGGGACATCGATCTTACTCATTTTCTCG296                            AlaGlnLeuGlyTrpIleAlaGlyThrSerIleLeuLeuIlePheSer                               65707580                                                                       TTCATTACTTACTTCACCTCCACCATGCTTGCCGATTGCTACCGTGCG344                            PheIleThrTyrPheThrSerThrMetLeuAlaAspCysTyrArgAla                               859095                                                                         CCGGATCCCGTCACCGGAAAACGGAATTACACTTACATGGACGTTGTT392                            ProAspProValThrGlyLysArgAsnTyrThrTyrMetAspValVal                               100105110                                                                      CGATCTTACCTCGGTGGTAGGAAAGTGCAGCTCTGTGGAGTGGCACAA440                            ArgSerTyrLeuGlyGlyArgLysValGlnLeuCysGlyValAlaGln                               115120125                                                                      TATGGGAATCTGATTGGGGTCACTGTTGGTTACACCATCACTGCTTCT488                            TyrGlyAsnLeuIleGlyValThrValGlyTyrThrIleThrAlaSer                               130135140                                                                      ATTAGTTTGGTAGCGGTAGGGAAATCGAACTGCTTCCACGATAAAGGG536                            IleSerLeuValAlaValGlyLysSerAsnCysPheHisAspLysGly                               145150155160                                                                   CACACTGCGGATTGTACTATATCGAATTATCCGTATATGGCGGTTTTT584                            HisThrAlaAspCysThrIleSerAsnTyrProTyrMetAlaValPhe                               165170175                                                                      GGTATCATTCAAGTTATTCTTAGCCAGATCCCAAATTTCCACAAGCTC632                            GlyIleIleGlnValIleLeuSerGlnIleProAsnPheHisLysLeu                               180185190                                                                      TCTTTTCTTTCCATTATGGCCGCAGTCATGTCCTTTACTTATGCAACT680                            SerPheLeuSerIleMetAlaAlaValMetSerPheThrTyrAlaThr                               195200205                                                                      ATTGGAATCGGTCTAGCCATCGCAACCGTCGCAGGTGGGAAAGTGGGT728                            IleGlyIleGlyLeuAlaIleAlaThrValAlaGlyGlyLysValGly                               210215220                                                                      AAGACGAGTATGACGGGCACAGCGGTTGGAGTAGATGTAACCGCAGCT776                            LysThrSerMetThrGlyThrAlaValGlyValAspValThrAlaAla                               225230235240                                                                   CAAAAGATATGGAGATCGTTTCAAGCGGTTGGGGACATAGCGTTCGCC824                            GlnLysIleTrpArgSerPheGlnAlaValGlyAspIleAlaPheAla                               245250255                                                                      TATGCTTATGCCACGGTTCTCATCGAGATTCAGGATACACTAAGATCT872                            TyrAlaTyrAlaThrValLeuIleGluIleGlnAspThrLeuArgSer                               260265270                                                                      AGCCCAGCTGAGAACAAAGCCATGAAAAGAGCAAGTCTTGTGGGAGTA920                            SerProAlaGluAsnLysAlaMetLysArgAlaSerLeuValGlyVal                               275280285                                                                      TCAACCACCACTTTTTTCTACATCTTATGTGGATGCATCGGCTATGCT968                            SerThrThrThrPhePheTyrIleLeuCysGlyCysIleGlyTyrAla                               290295300                                                                      GCATTTGGAAACAATGCCCCTGGAGATTTCCTCACAGATTTCGGGTTT1016                           AlaPheGlyAsnAsnAlaProGlyAspPheLeuThrAspPheGlyPhe                               305310315320                                                                   TTCGAGCCCTTTTGGCTCATTGACTTTGCAAACGCTTGCATCGCTGTC1064                           PheGluProPheTrpLeuIleAspPheAlaAsnAlaCysIleAlaVal                               325330335                                                                      CACCTTATTGGTGCCTATCAGGTGTTCGCGCAGCCGATATTCCAGTTT1112                           HisLeuIleGlyAlaTyrGlnValPheAlaGlnProIlePheGlnPhe                               340345350                                                                      GTTGAGAAAAAATGCAACAGAAACTATCCAGACAACAAGTTCATCACT1160                           ValGluLysLysCysAsnArgAsnTyrProAspAsnLysPheIleThr                               355360365                                                                      TCTGAATATTCAGTAAACGTACCTTTCCTTGGAAAATTCAACATTAGC1208                           SerGluTyrSerValAsnValProPheLeuGlyLysPheAsnIleSer                               370375380                                                                      CTCTTCAGATTGGTGTGGAGGACAGCTTATGTGGTTATAACCACTGTT1256                           LeuPheArgLeuValTrpArgThrAlaTyrValValIleThrThrVal                               385390395400                                                                   GTAGCTATGATATTCCCTTTCTTCAACGCGATCTTAGGTCTTATCGGA1304                           ValAlaMetIlePheProPhePheAsnAlaIleLeuGlyLeuIleGly                               405410415                                                                      GCAGCTTCCTTCTGGCCTTTAACGGTTTATTTCCCTGTGGAGATGCAC1352                           AlaAlaSerPheTrpProLeuThrValTyrPheProValGluMetHis                               420425430                                                                      ATTGCACAAACCAAGATTAAGAAGTACTCTGCTAGATGGATTGCGCTG1400                           IleAlaGlnThrLysIleLysLysTyrSerAlaArgTrpIleAlaLeu                               435440445                                                                      AAAACGATGTGCTATGTTTGCTTGATCGTCTCGCTCTTAGCTGCAGCC1448                           LysThrMetCysTyrValCysLeuIleValSerLeuLeuAlaAlaAla                               450455460                                                                      GGATCCATCGCAGGACTTATAAGTAGTGTCAAAACCTACAAGCCCTTC1496                           GlySerIleAlaGlyLeuIleSerSerValLysThrTyrLysProPhe                               465470475480                                                                   CGGACTATGCATGAGTGAGTTTGAGATCCTCAAGAGAGTCAAAAATATATGTAGT1551                    ArgThrMetHisGlu                                                                485                                                                            AGTTTGGTCTTTCTGTTAAACTATCTGGTGTCTAAATCCAATGAGAATGCTTTATTGCTA1611               AAACTTCATGAATCTCTCTGTATCTACATCTTTCAATCTAATACATATGAGCTCTTCCAA1671               AAAAAAAAAAAAAA1685                                                             (2) INFORMATION FOR SEQ ID NO:2:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 485 amino acids                                                    (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                        MetLysSerPheAsnThrGluGlyHisAsnHisSerThrAlaGluSer                               151015                                                                         GlyAspAlaTyrThrValSerAspProThrLysAsnValAspGluAsp                               202530                                                                         GlyArgGluLysArgThrGlyThrTrpLeuThrAlaSerAlaHisIle                               354045                                                                         IleThrAlaValIleGlySerGlyValLeuSerLeuAlaTrpAlaIle                               505560                                                                         AlaGlnLeuGlyTrpIleAlaGlyThrSerIleLeuLeuIlePheSer                               65707580                                                                       PheIleThrTyrPheThrSerThrMetLeuAlaAspCysTyrArgAla                               859095                                                                         ProAspProValThrGlyLysArgAsnTyrThrTyrMetAspValVal                               100105110                                                                      ArgSerTyrLeuGlyGlyArgLysValGlnLeuCysGlyValAlaGln                               115120125                                                                      TyrGlyAsnLeuIleGlyValThrValGlyTyrThrIleThrAlaSer                               130135140                                                                      IleSerLeuValAlaValGlyLysSerAsnCysPheHisAspLysGly                               145150155160                                                                   HisThrAlaAspCysThrIleSerAsnTyrProTyrMetAlaValPhe                               165170175                                                                      GlyIleIleGlnValIleLeuSerGlnIleProAsnPheHisLysLeu                               180185190                                                                      SerPheLeuSerIleMetAlaAlaValMetSerPheThrTyrAlaThr                               195200205                                                                      IleGlyIleGlyLeuAlaIleAlaThrValAlaGlyGlyLysValGly                               210215220                                                                      LysThrSerMetThrGlyThrAlaValGlyValAspValThrAlaAla                               225230235240                                                                   GlnLysIleTrpArgSerPheGlnAlaValGlyAspIleAlaPheAla                               245250255                                                                      TyrAlaTyrAlaThrValLeuIleGluIleGlnAspThrLeuArgSer                               260265270                                                                      SerProAlaGluAsnLysAlaMetLysArgAlaSerLeuValGlyVal                               275280285                                                                      SerThrThrThrPhePheTyrIleLeuCysGlyCysIleGlyTyrAla                               290295300                                                                      AlaPheGlyAsnAsnAlaProGlyAspPheLeuThrAspPheGlyPhe                               305310315320                                                                   PheGluProPheTrpLeuIleAspPheAlaAsnAlaCysIleAlaVal                               325330335                                                                      HisLeuIleGlyAlaTyrGlnValPheAlaGlnProIlePheGlnPhe                               340345350                                                                      ValGluLysLysCysAsnArgAsnTyrProAspAsnLysPheIleThr                               355360365                                                                      SerGluTyrSerValAsnValProPheLeuGlyLysPheAsnIleSer                               370375380                                                                      LeuPheArgLeuValTrpArgThrAlaTyrValValIleThrThrVal                               385390395400                                                                   ValAlaMetIlePheProPhePheAsnAlaIleLeuGlyLeuIleGly                               405410415                                                                      AlaAlaSerPheTrpProLeuThrValTyrPheProValGluMetHis                               420425430                                                                      IleAlaGlnThrLysIleLysLysTyrSerAlaArgTrpIleAlaLeu                               435440445                                                                      LysThrMetCysTyrValCysLeuIleValSerLeuLeuAlaAlaAla                               450455460                                                                      GlySerIleAlaGlyLeuIleSerSerValLysThrTyrLysProPhe                               465470475480                                                                   ArgThrMetHisGlu                                                                485                                                                            (2) INFORMATION FOR SEQ ID NO:3:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 1740 base pairs                                                    (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arabidopsis thaliana                                             (ix) FEATURE:                                                                  (A) NAME/KEY: CDS                                                              (B) LOCATION: 80..1558                                                         (D) OTHER INFORMATION: /product="amino acid transporter"                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                        CTATTTTATAATTCCTCTTCTTTTTGTTCATAGCTTTGTAATTATAGTCTTATTTCTCTT60                 TAAGGCTCAATAAGAGGAGATGGGTGAAACCGCTGCCGCCAATAACCACCGT112                        MetGlyGluThrAlaAlaAlaAsnAsnHisArg                                              1510                                                                           CACCACCACCATCACGGCCACCAGGTCTTTGACGTGGCCAGCCACGAT160                            HisHisHisHisHisGlyHisGlnValPheAspValAlaSerHisAsp                               152025                                                                         TTCGTCCCTCCACAACCGGCTTTTAAATGCTTCGATGATGATGGCCGC208                            PheValProProGlnProAlaPheLysCysPheAspAspAspGlyArg                               303540                                                                         CTCAAAAGAACTGGGACTGTTTGGACCGCGAGCGCTCATATAATAACT256                            LeuLysArgThrGlyThrValTrpThrAlaSerAlaHisIleIleThr                               455055                                                                         GCGGTTATCGGATCCGGCGTTTTGTCATTGGCGTGGGCGATTGCACAG304                            AlaValIleGlySerGlyValLeuSerLeuAlaTrpAlaIleAlaGln                               60657075                                                                       CTCGGATGGATCGCTGGCCCTGCTGTGATGCTATTGTTCTCTCTTGTT352                            LeuGlyTrpIleAlaGlyProAlaValMetLeuLeuPheSerLeuVal                               808590                                                                         ACTCTTTACTCCTCCACACTTCTTAGCGACTGCTACAGAACCGGCGAT400                            ThrLeuTyrSerSerThrLeuLeuSerAspCysTyrArgThrGlyAsp                               95100105                                                                       GCAGTGTCTGGCAAGAGAAACTACACTTACATGGATGCCGTTCGATCA448                            AlaValSerGlyLysArgAsnTyrThrTyrMetAspAlaValArgSer                               110115120                                                                      ATTCTCGGTGGGTTCAAGTTCAAGATTTGTGGGTTGATTCAATACTTG496                            IleLeuGlyGlyPheLysPheLysIleCysGlyLeuIleGlnTyrLeu                               125130135                                                                      AATCTCTTTGGTATCGCAATTGGATACACGATAGCAGCTTCCATAAGC544                            AsnLeuPheGlyIleAlaIleGlyTyrThrIleAlaAlaSerIleSer                               140145150155                                                                   ATGATGGCGATCAAGAGATCCAACTGCTTCCACAAGAGTGGAGGAAAA592                            MetMetAlaIleLysArgSerAsnCysPheHisLysSerGlyGlyLys                               160165170                                                                      GACCCATGTCACATGTCCAGTAATCCTTACATGATCGTATTTGGTGTG640                            AspProCysHisMetSerSerAsnProTyrMetIleValPheGlyVal                               175180185                                                                      GCAGAGATCTTGCTCTCTCAGGTTCCTGATTTCGATCAGATTTGGTGG688                            AlaGluIleLeuLeuSerGlnValProAspPheAspGlnIleTrpTrp                               190195200                                                                      ATCTCCATTGTTGCAGCTGTTATGTCCTTCACTTACTCTGCCATTGGT736                            IleSerIleValAlaAlaValMetSerPheThrTyrSerAlaIleGly                               205210215                                                                      CTAGCTCTTGGAATCGTTCAAGTTGCAGCGAATGGAGTTTTCAAAGGA784                            LeuAlaLeuGlyIleValGlnValAlaAlaAsnGlyValPheLysGly                               220225230235                                                                   AGTCTCACTGGAATAAGCATCGGAACAGTGACTCAAACACAGAAGATA832                            SerLeuThrGlyIleSerIleGlyThrValThrGlnThrGlnLysIle                               240245250                                                                      TGGAGAACCTTCCAAGCACTTGGAGACATTGCCTTTGCGTACTCATAC880                            TrpArgThrPheGlnAlaLeuGlyAspIleAlaPheAlaTyrSerTyr                               255260265                                                                      TCTGTTGTCCTAATCGAGATTCAGGATACTGTAAGATCCCCACCGGCG928                            SerValValLeuIleGluIleGlnAspThrValArgSerProProAla                               270275280                                                                      GAATCGAAAACGATGAAGAAAGCAACAAAAATCAGTATTGCCGTCACA976                            GluSerLysThrMetLysLysAlaThrLysIleSerIleAlaValThr                               285290295                                                                      ACTATCTTCTACATGCTATGTGGCTCAATGGGTTATGCCGCTTTTGGA1024                           ThrIlePheTyrMetLeuCysGlySerMetGlyTyrAlaAlaPheGly                               300305310315                                                                   GATGCAGCACCGGGAAACCTCCTCACCGGTTTTGGATTCTACAACCCG1072                           AspAlaAlaProGlyAsnLeuLeuThrGlyPheGlyPheTyrAsnPro                               320325330                                                                      TTTTGGCTCCTTGACATAGCTAACGCCGCCATTGTTGTCCACCTCGTT1120                           PheTrpLeuLeuAspIleAlaAsnAlaAlaIleValValHisLeuVal                               335340345                                                                      GGAGCTTACCAAGTCTTTGCTCAGCCCATCTTTGCCTTTATTGAAAAA1168                           GlyAlaTyrGlnValPheAlaGlnProIlePheAlaPheIleGluLys                               350355360                                                                      TCAGTCGCAGAGAGATATCCAGACAATGACTTCCTCAGCAAGGAATTT1216                           SerValAlaGluArgTyrProAspAsnAspPheLeuSerLysGluPhe                               365370375                                                                      GAAATCAGAATCCCCGGATTTAAGTCTCCTTACAAAGTAAACGTTTTC1264                           GluIleArgIleProGlyPheLysSerProTyrLysValAsnValPhe                               380385390395                                                                   AGGATGGTTTACAGGAGTGGCTTTGTCGTTACAACCACCGTGATATCG1312                           ArgMetValTyrArgSerGlyPheValValThrThrThrValIleSer                               400405410                                                                      ATGCTGATGCCGTTTTTTAACGACGTGGTCGGGATCTTAGGGGCGTTA1360                           MetLeuMetProPhePheAsnAspValValGlyIleLeuGlyAlaLeu                               415420425                                                                      GGGTTTTGGCCCTTGACGGTTTATTTTCCGGTGGAGATGTATATTAAG1408                           GlyPheTrpProLeuThrValTyrPheProValGluMetTyrIleLys                               430435440                                                                      CAGAGGAAGGTTGAGAAATGGAGCACGAGATGGGTGTGTTTACAGATG1456                           GlnArgLysValGluLysTrpSerThrArgTrpValCysLeuGlnMet                               445450455                                                                      CTTAGTGTTGCTTGTCTTGTGATCTCGGTGGTCGCCGGGGTTGGATCA1504                           LeuSerValAlaCysLeuValIleSerValValAlaGlyValGlySer                               460465470475                                                                   ATCGCCGGAGTGATGCTTGATCTTAAGGTCTATAAGCCATTCAAGTCT1552                           IleAlaGlyValMetLeuAspLeuLysValTyrLysProPheLysSer                               480485490                                                                      ACATATTGATGATTATGGACCATGAACAACAGAGAGAGTTGGTGTGTAAAGTTTAC1608                   ThrTyr                                                                         CATTTCAAAGAAAACTCCAAAAATGTGTATATTGTATGTTGTTCTCATTTCGTATGGTCT1668               CATCTTTGTAATAAAATTTAAAACTTATGTTATAAATTATAAAAAAAAAAAAAAAAAAAA1728               AAAAAAAAAAAA1740                                                               (2) INFORMATION FOR SEQ ID NO:4:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 493 amino acids                                                    (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                        MetGlyGluThrAlaAlaAlaAsnAsnHisArgHisHisHisHisHis                               151015                                                                         GlyHisGlnValPheAspValAlaSerHisAspPheValProProGln                               202530                                                                         ProAlaPheLysCysPheAspAspAspGlyArgLeuLysArgThrGly                               354045                                                                         ThrValTrpThrAlaSerAlaHisIleIleThrAlaValIleGlySer                               505560                                                                         GlyValLeuSerLeuAlaTrpAlaIleAlaGlnLeuGlyTrpIleAla                               65707580                                                                       GlyProAlaValMetLeuLeuPheSerLeuValThrLeuTyrSerSer                               859095                                                                         ThrLeuLeuSerAspCysTyrArgThrGlyAspAlaValSerGlyLys                               100105110                                                                      ArgAsnTyrThrTyrMetAspAlaValArgSerIleLeuGlyGlyPhe                               115120125                                                                      LysPheLysIleCysGlyLeuIleGlnTyrLeuAsnLeuPheGlyIle                               130135140                                                                      AlaIleGlyTyrThrIleAlaAlaSerIleSerMetMetAlaIleLys                               145150155160                                                                   ArgSerAsnCysPheHisLysSerGlyGlyLysAspProCysHisMet                               165170175                                                                      SerSerAsnProTyrMetIleValPheGlyValAlaGluIleLeuLeu                               180185190                                                                      SerGlnValProAspPheAspGlnIleTrpTrpIleSerIleValAla                               195200205                                                                      AlaValMetSerPheThrTyrSerAlaIleGlyLeuAlaLeuGlyIle                               210215220                                                                      ValGlnValAlaAlaAsnGlyValPheLysGlySerLeuThrGlyIle                               225230235240                                                                   SerIleGlyThrValThrGlnThrGlnLysIleTrpArgThrPheGln                               245250255                                                                      AlaLeuGlyAspIleAlaPheAlaTyrSerTyrSerValValLeuIle                               260265270                                                                      GluIleGlnAspThrValArgSerProProAlaGluSerLysThrMet                               275280285                                                                      LysLysAlaThrLysIleSerIleAlaValThrThrIlePheTyrMet                               290295300                                                                      LeuCysGlySerMetGlyTyrAlaAlaPheGlyAspAlaAlaProGly                               305310315320                                                                   AsnLeuLeuThrGlyPheGlyPheTyrAsnProPheTrpLeuLeuAsp                               325330335                                                                      IleAlaAsnAlaAlaIleValValHisLeuValGlyAlaTyrGlnVal                               340345350                                                                      PheAlaGlnProIlePheAlaPheIleGluLysSerValAlaGluArg                               355360365                                                                      TyrProAspAsnAspPheLeuSerLysGluPheGluIleArgIlePro                               370375380                                                                      GlyPheLysSerProTyrLysValAsnValPheArgMetValTyrArg                               385390395400                                                                   SerGlyPheValValThrThrThrValIleSerMetLeuMetProPhe                               405410415                                                                      PheAsnAspValValGlyIleLeuGlyAlaLeuGlyPheTrpProLeu                               420425430                                                                      ThrValTyrPheProValGluMetTyrIleLysGlnArgLysValGlu                               435440445                                                                      LysTrpSerThrArgTrpValCysLeuGlnMetLeuSerValAlaCys                               450455460                                                                      LeuValIleSerValValAlaGlyValGlySerIleAlaGlyValMet                               465470475480                                                                   LeuAspLeuLysValTyrLysProPheLysSerThrTyr                                        485490                                                                         __________________________________________________________________________ 

I claim:
 1. An isolated DNA sequence consisting of the coding region of SEQ ID NO:1.
 2. An isolated DNA sequence consisting of the coding region of SEQ ID NO:3.
 3. An isolated nucleotide sequence encoding an amino acid sequence as shown in SEQ ID NO:2.
 4. An isolated nucleotide sequence encoding an amino acid sequence as shown in SEQ ID NO:4.
 5. A plasmid comprising the DNA sequence consisting of the coding region of SEQ ID NO:
 1. 6. A plasmid comprising the DNA sequence consisting of the coding region of SEQ ID NO:3.
 7. The plasmid pPPP1-20.
 8. The plasmid pBin PPP1-20.
 9. The plasmid pAAP2.
 10. A plasmid comprising:a promoter sequence; a DNA sequence selected from the group consisting of the DNA sequence of the coding region of SEQ ID NO: 1 and the DNA sequence of the coding region of SEQ ID NO:3; and a transcriptional termination sequence, wherein said sequences are operably linked.
 11. A plasmid, as recited in claim 10, wherein said DNA sequence is in a sense orientation.
 12. A plasmid, as recited in claim 10, wherein said DNA sequence is in an anti-sense orientation.
 13. A method of producing a transformed eukaryotic or prokaryotic cell, comprising the step of:transforming a eukaryotic or prokaryotic cell with a plasmid selected from the group consisting of plasmid pPP1-20, plasmid pBin PPP 1 -20, and plasmid pAAP2.
 14. A method of producing a eukaryotic or prokaryotic cell that expresses an increased amount of an amino acid transporter relative to a non-transformed cell, comprising the step of:transforming a eukaryotic or prokaryotic cell with a plasmid according to claim 11, wherein said transformed cell expresses an increased amount of an amino acid transporter relative to a non-transformed cell.
 15. A method of producing a eukaryotic or prokaryotic cell that expresses a decreased amount of an amino acid transporter relative to a non-transformed cell, comprising the step of:transforming a eukaryotic or prokaryotic cell with a plasmid according to claim 12, wherein said transformed cell expresses a decreased amount of an amino acid transporter relative to a non-transformed cell.
 16. A method of altering the transport of amino acids in a prokaryotic or eukaryotic cell comprising the step of:transforming a cell with a DNA sequence selected from the group consisting of the DNA sequence consisting of the coding region of SEQ ID NO: 1 and the DNA sequence consisting of the coding region of SEQ ID NO:3.
 17. A cell transformed with a plasmid selected from the group consisting of plasmid pPPP1-20, plasmid pBin PPP1-20, and plasmid pAAP2, wherein said cell expresses an altered amount of amino acid transporter activity relative to a non-transformed cell.
 18. A bacterium transformed with the DNA sequence consisting of the coding region of SEQ ID NO:1.
 19. A bacterium transformed with the DNA sequence consisting of the coding region of SEQ ID NO:3.
 20. A yeast strain transformed with the DNA sequence consisting of the coding region of SEQ ID NO:1.
 21. A yeast strain transformed with the DNA sequence consisting of the coding region of SEQ ID NO:3.
 22. A transgenic plant comprising a DNA sequence selected from the group consisting of SEQ ID NO:1 and SEQ ID NO:3. 